Civil Engineering Reference
In-Depth Information
14.2.2.2 Buckling analysis of a pony truss
by Timoshenko's method
Length of vertical members = l
l
(as shown in Figure 14.7)
Modulus of elasticity =
E
Moment of inertia of vertical members =
I
v
Length of floor beam =
d
(as shown in Figure 14.7)
Moment of inertia of floor beam =
I
b
Length of diagonal members =
a
Moment of inertia of diagonals =
I
d
Length of each panel = 2
c
Total length of all top chord members =
L
Moment of inertia of top chord members =
I
t
1. Calculate the modulus of equivalent elastic foundation
a. Vertical members
3
2
l
EI
l d
EI
1
A
=
B
=
R
=
01
A B
+
3
2
v
b
b. Diagonal members
3
2
a
EI
l d
EI
2
A
=
B
=
R
=
02
A B
+
3
2
v
b
c. Considering all parts
3
l
a
I
=
I
+
2
I
eq
v
d
3
2
l
EI
l d
EI
1
A
=
B
=
R
=
02
A B
+
3
2
eq
b
2. Calculating the buckling load
Calculate
b
2
R
c
π
EI
L
0
t
b
=
P
=
e
4
16/
and find out 1/
m
from the following table by
interpolating
Calculate
bL
EI
t
bL
4
/16
EI
t
0
5
10
15
22.8
56.5
100 162.8
200
300
500
1000
1/m
0.696 0.524 0.443 0.396 0.363 0.324 0.29 0.259 0.246 0.225 0.204 0.174
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